Terragraph arrives in Mikebuda, Hungary

Deutsche Telekom partnered with Facebook to evaluate Terragraph as a fixed wireless access solution. Deutsche Telekom and its subsidiary in Hungary, Magyar Telekom, worked with Facebook to deploy a Terragraph trial using the reference design radios.

Two towns in Hungary were selected for trial locations with Magyar Telekom. The town of Mikebuda was selected for the first pre-commercial trial, and the town of Marko was selected as a second location. The Mikebuda trial began in May 2018, and the Marko trial in October 2018.

Magyar Telekom partnered with Facebook to evaluate Terragraph

Trial Location Selection

Facebook worked with Magyar Telekom’s team in Hungary to plan and design the network collaboratively. The planning began in early 2018 with a review of locations, from which Mikebuda and Marko were ultimately selected.

The following attributes were considered during the trial location selection phase:

• Magyar Telekom presence
• Existing broadband was DSL
• Fiber availability
• Sufficient street lights and utility poles for mounting radio equipment
• Light suburban density of homes

Mikebuda was deployed first, as the smaller of the trial locations, such that insights gained from this trial could be subsequently applied in the Marko deployment.

The goal of the installation in Mikebuda was to provide coverage to the entire small town about 0.4 sq km in size. There are approximately 150 single family homes in the town.

Existing Services in Mikebuda

Prior to the trial, Magyar Telekom had about 100 subscribers of their DSL service in Mikebuda and they were all approached for participation in the Terragraph trial. Of the 100 subscribers, 25 were also subscribing to IPTV Multicast services. The network in Mikebuda had two DSLAMs with about half the traffic on each. The peak speed out of the DSLAMs was approximately 15 Mbps and 40 Mbps peak, with the higher capacity version providing sufficient speed to support the multicast IPTV.

Service Model

With point-to-point layer-2 tunnels in place between the BNG and subscriber CPEs, it is possible for the service model to be exactly the same as it is for other fixed access platforms in Magyar Telekom’s portfolio. Once connected to the Terragraph network via a client node, the Mikrotik CPE establishes 2 pseudowires to the EoIPv6 tunnel terminator: one for HSI and one for IPTV. A PPPoE dialer in the CPE establishes connectivity to the BNG using pre-configured user credentials, thus enabling Internet access. Simultaneously the DHCP client running over the other pseudowire acquires an IPv4 address, activating the IPTV service. CPE management & configuration runs over TR-069 (over HTTPS) which can either run on the HSI connection or can be run on a separate tunnel or PPPoE session.

Terragraph allows you to efficiently extend the reach of your existing fiber network wirelessly throughout dense urban / suburban enviornments providing your customers reliable internet

— Jay Parikh, Head of Engineering and Infrastructure

RAN Planning

The process of planning a Terragraph network includes both the skills of microwave design and cellular system design: the links must be clear line of sight and within the high capacity operating range of the radio system. Unlike mobile networks, the RAN planning for a fixed network can be targeted precisely in the area of interest prior to marketing and sales. For example, in a large city an operator can select a small region and deploy their first Terragraph to hone the process and test the market.

Permitting and Related Permissions

To meet regional regulatory requirements, a set of permits was required prior to installation of the equipment, this included:

• License for 60 GHz operation: Currently, outdoor use of 60 GHz must be operated under a temporary license, which was secured early in the process. Note that once ETSI grants the unlicensed use of the 60GHz band, anticipated in 2019, this requirement will go away.
• Utility Poles: The utility company in Mikebuda owns and operates the poles employed in the design. Many of the poles already had 3rd party service equipment. Additionally, maintenance of the poles is typically performed using a ladder rather than a utility vehicle (“bucket truck”). This required that the radios be mounted in such a way to not impede this process. Both the utility company and the other firms operating the poles granted permission to the team.
• POP site: Magyar Telekom required permission from the municipality to use the local buildings as the POP site and to install radio equipment.
• Foliage Issues: In some cases there were minor obstruction from local foliage. In these areas, permission was required from the municipality to trim the foliage to remove the obstruction

Installation

After collection of the appropriate permits and permission completed, the installation of the radios commenced

Deployment was completed in two phases:

1. Deployment and optimization of the distribution network – i.e. the mesh network which covers the entire service area, including the fiber PoPs
2. Deployment of subscriber equipment

The deployment of the distribution network was accomplished in less than 2 weeks. Each site installation took approximately 2 hours

Once the distribution network had been deployed, the ~106 homes within its coverage area were then eligible for high speed fixed wireless access.

Trial Outcomes

The Terragraph network in Mikebuda has been operating for multiple months now, delivering high speed broadband connectivity to approximately half the households within its coverage area. Some statistics at a glance include:

• 50 customers connected as of the writing of this paper
• 106 homes covered over a service area of approximately 0.4 sqkm
• Peak measured speeds in the trial have been measured as ~1Gbps at the Terragraph client nodes, and 650 Mbps at the indoor CPE (wired). Note that the CPE speed limitation relative to the Terragraph CN is due to the limited rate at which the CPE can perform the tunnel encapsulation & decapsulation for EoIPv6. Peak in-home Wi-Fi speeds are in the range of 300 Mbps, limited by the Wi-Fi air interface itself (2×2 802.11ac over 40MHz channels).
• Average service availability of 99.5% or better.

Customer Experience

Customers are experiencing speeds up to 10-100 times faster than their previous connections (5-10 Mbps with DSL to 500 Mbps with Terragraph). Likewise, the IPTV customers have been impressed with the service. The first customer noting, “This is pristine clear! The one we had before was a mess.”

Mikebuda Trial Takeaways

Terregraph offers a huge advantage in terms of time to deploy

The speed at which the Terragraph network was deployed in Mikebuda was noteworthy. In just two weeks, over a hundred households were covered with the option to subscribe to services. Subsequent customer connections were completed on the order of hours each. Alternative infrastructures capable of delivering similar connection speeds – i.e. fiber – would likely have taken several times longer to deploy.

Of course this being the first fixed wireless access trial deployment for Terragraph, there were multiple opportunities identified to further reduce the time to deploy – e.g. through refinement of best practices and workflow – as well as enhancements to the software tools used during deployment. These learnings will be put into practice for the Marko trial, which is therefore expected to demonstrate even faster deployment speed.

Terragraph offers Gigabit-speeds with a much higher flexibility of deployment than fiber

Based on the results from the trial and projected commercial costs it is estimated that Terragraph CapEx per home covered will be as low as 30% of that of an equivalent buried fiber build in some markets. Now that the Mikebuda trial has reached operational “steady state”, OpEx will also be measured and factored in to the cost analysis.

The line of sight requirement for mmWave links is manageable

Mikebuda was not without its line of sight challenges. Careful sight survey and network design was required to avoid placing Terragraph nodes in locations with limited visibility to other nodes and/or subscriber households. A small amount of tree-trimming was also required to clear line of sight for some links. The challenge was manageable, as evidenced by the resulting network with healthy performance, however there is clearly an opportunity for additional solutions. In Marko for example, the trial will experiment with sub-6GHz links to overcome foliage blockage in a handful of cases. Network planning tools will also play an important role in designing around line of sight constraints.

Availability of the Terragraph solution lives up to the requirements of fixed broadband service

The Terragraph network in Mikebuda demonstrates availability in excess of 99.5%, which is viewed as a reasonable threshold for broadband internet service. One of the main challenges in terms of availability is power interruption. For example, power outages that affect sections of the town including the poles from which the Terragraph nodes draw power or subscribers unplugging power to the client node mounted to their house.

Outlook

The trial in Mikebuda is a compelling demonstration of Terragraph as a fixed wireless access solution, delivering fiber-like speeds to residential customers at a fraction of the cost of buried fiber. The trial outcomes support the case for the commercial viability of Terragraph, and its potential to make a real impact towards the the connectivity goal of connecting more people to a faster internet. Leading OEMs are in fact already well underway towards commercializing the solution: Terragraphcertified product will be available from OEMs starting in 2019, enabling commercial deployment of the technology.

In the interim, field trials are of utmost value as they present an opportunity for the ecosystem to gain further solution insights, such as:

• Deployment best practices
• Opportunities to reduce cost and/or time to deploy
• Product requirements and feature insights
• Business insights
• Insights related to location-specific deployment challenges.

Facebook remains committed to supporting Terragraph trials, including the second trial with Magyar Telekom in Marko, Hungary, as well as trials with service providers in other parts of the world.